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Immunology and Microbiology > Viruses > Flashcards

Flashcards in Viruses Deck (22):
1

Influenza Genome

ssRNA

2

Influenza structure (main proteins) (4)

HA, NA, M2, M1

3

Influenza cell entry (5)

(1) three spikes of HA bind to sialic acid on HC
(2) receptor mediated endocytosis occurs
(3) low endosomal pH triggers fusion of viral and endosome membrane - low pH induces conformational change in shape of H0 - leads to exposure of HA2 fusion peptide
(4) low pH also opens M2 proton selective channel - acidifies viral core
(5) release of vRNP so free to enter host cell cytoplasm

4

Influenza transcription and replication (2)

(1) converted to positive sense RNA by RNA dependent RNA polymerase (RdRp)
(2) cellular RNA polymerase II binds to DNA and starts transcripiton

5

Influenza immune responses (3)

1. induces strong IFN production - induces non-permissive state in neighbouring cells
2. humoral mediated immunity - HA specific antibodies found
3. RIG-1 is main PRR against influenza virus infections

6

Influenza M2 ion channel inhibiting drugs

Amantadine and Rimantadine

7

Influenza RNA polymerase inhibitor

Favipiravir

8

Influenza NA inhibitor

Zanamivir

9

Herpes Genome

dsDNA

10

HHV-1

Herpes simplex - cold sore - trigeminal ganglion infection (60% US prevalance)

11

HHV-2

Herpes simplex - genital herpes - sacral ganglion (20% US prevalence)

12

HHV-3

Varicella (chicken pox) Zoster (shingles) virus

13

HHV-4

Epstein Virus

14

Herpes Cell entry (6)

1. gC and gB bind to heparan sulfate
2. gD binds to HVEM, nectin-q, or 3-0 sulfated heparan sulphate
3. nectin receptors produce cell-cell adhesion
4. gD (once bound to HVEM), changes conformation and interacts with gH and gL
5. interaction results in hemifusion state
6. gB interaction with gH/gL results in creation of entry pore

15

Herpes Virus immune evasion (4)

1. Block MHC I expression and promote degradation
2. inhibit proteosome
3. block TAP transporter
4. block expression of activatory NK ligands

16

Herpes virus treatment (1)

acyclovir and glancyclovir - thymidine anlogues

17

HIV genome

ssRNA

18

HIV cell entry (4)

1. Gp120 binds to CD4
2. co-receptor binding (CCR5/CXCR4)
3. interaction between CD4 and gp120 allows exposure of fusion proteins in the gp41 subunit - inserts into host cell membrane and acts as a tether
4. mixing of lipids which compose the membranes and entry

19

HIV replication (4)

Uses Reverse Transcriptase
1. polymerase center uses host cell tRNA to use viral RNA as a template - RNA-DNA strand formed
2. RNaseH center used to degrade RNA component
3. dsDNA formed
4. integrase effectively cuts and pastes the viral DNA in to the gebome

20

HIV transcription

1. immediately after replication, only Tat and Rev produced
2. Tat increases transcription of HIV-1 genes by recruiting cellular transcription factors
3. primary RNA transcripts undergo extensive splicing - results in over 40 different mRNAs

21

HIV antiviral drugs (3)

Tak-220 - prevents binding of CCR5 to gp120
Enfuvirtide - targets membrane fusion
Zidovudine - thymidine analogue which prevents action of RT

22

Hepatitis Genome

dsDNA